Differences

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--- family_relations [2026/09/23 10:01] – trynke
+++ family_relations [2026/10/05 12:21] (current) – jasper
@@ Line 23: / Line 23: @@
 The identifiers can be used to pair the family data to other phenotypic and genotypic data. The same participant identifier can also be found in the column for father or mother and partner. In which column the identifier can be found, depends on the participant's family size and if they are, for example, both a child and a parent. With the use of self reported data on family members like birthdays of parents and siblings, family members shared between siblings could be derived. These are family members that do not participate in Lifelines. Other than the family member connection, we do not have any other information on these persons. These derived family members have received a unique identifier (an S-number, i.e. S1031206). This identifier cannot be used to pair the data to other Lifelines data. An example is when two siblings have indicated to have the same parent; the (non-participating) parent has then received an S-number.
 The family id is used to identify participants that are part of the same family. Couples who share a household, but don't have children, also receive a family id. This provides the opportunity to work on research involving environmental factors. Note that partner information is based on [[1A|baseline data]].
+===== Interpretation of FAM_ID (Family id) =====
+In the family relations file, FAM_ID was updated following quality control of the genetic data. If first-degree relatives were identified who linked two or more previously separate families, these families were merged under a single FAM_ID. In such cases, one of the existing FAM_IDs was retained and the others were removed.
+Importantly, participants sharing the same FAM_ID are not necessarily all genetically related to one another. A family group may include multiple participants who are connected through both genetic and non-genetic relationships. For example, siblings and their respective partners may all share the same FAM_ID, even though the partners are not genetically related to each other or to their partner’s sibling.
+It is also possible for a participant who is not genetically related to the other members of their original family group, such as a partner, to be identified through the genetic data as a first-degree relative of someone in another family. In that case, the two family groups were also merged, and all participants in both groups were assigned the same FAM_ID.
+Therefore, FAM_ID should be interpreted as identifying a connected family group rather than a group in which every participant is genetically related to every other participant.
 ===== Family Duos and Trios =====